Bugs: Streptococcus pneumoniae and Enterococcus Flashcards
Strep Pneumoniae:
Bacteriology -
biochemical tests
Gram Positive cocci Chains
Catalase negative
Alpha hemolysis
Optochin positive (quelling) – aka no growth around optochin disk
Describe some virulence factors of S. pneumo
Evades the immune system: capsule, pneumolysisn
Adheres to host – phosphocholine, and other adhesion proteins
Strep Pneumo:
- Risk factors for disease
- Colonization
colonizes naso and oropharynx in 40-60% of adults
Risk factors for disease:
Not getting vaccinated
Splenectomy (less protection against encapsulated bacteria)
Immunodeficiencies
low functioning PMNs (alcoholics, liver disease, renal disease)
COPD, smoking, asthma
What are the clinical manifestations of S pneumo?
Briefly discuss some treatments
most common cause of meningitis in adults
otitis media – most common bacterial isolate (amoxicillin)
sinusitis
bronchitis
bacteremia
How is strep pneumo meningitis treated?
Ceftriaxone; back up vancomycin
– MUST START TREATMENT AS EARLY AS POSSIBLE
How strep pneumo, pneumonia treated ?
Ceftriaxone;
macrolides to cover the atypicals (legionella, mycoplasma, chlamydia)
What are the vaccines for Strep Pneumo?
Pneumovax – adults
Prevnar – children
Pathogenesis: How does strep pneumo go from colonization to disease?
Colonizes the oral and naso mucosa
when its moves into areas that should be sterile and becomes trapped there; becomes disease
eg – viral trapping
Enterococcus:
bacteriology
biochemical tests
where do they colonize
Gram postiive cocci
Shorts pairs and chains
facultative anaerobe
Catalase Negative
PYR positive
LAP positive
colonize the GI (‘entero’ = enteric)
pathogenesis: How do colonizing enterococci become infectious ?
abx in the gut can alter intestinal flora, favoring enterococci growth
Abx may also downregulate the intestinal antimicrobial - RegIIIy
What are some virulence factors of Enterococci ?
what is its most important virulence factor?
Surface adhesion
Tissue Damage - cytolysins and proteases
Stress proteins
Most Important virulence factor is Abx resistance:
Inherently resistant to Cephalosporins
Acquired resistance to: aminoglycosides, FQs, Vanc
What are the two clinically important species of enterococci?
describe the difference in the treatment regimen of the two
E. fecalis — susceptible to PCN/ampicillin
non endocarditis: 1 abx needed (ampicillin)
endocarditis: 2 abx needed (ampiciilin + gentimicin)
E. faecium — RESISTANCE TO AMPICILLIN
Non endocarditis: Vancomycin
Endocarditis: Vanco + gentimicin
What is the mechanism of resistance of VRE
D ala Dala –> D ala D lac
what are two peripheral signs of endocarditis?
Janeway lesion – on palm – painless
Osler node – on thumb – painful
What are some risk factors for acquiring endo?
Second most common Nosocomial infection in the US
